1. Field of the Invention
This application relates to network designs for delivering communication services to customer devices, and more particularly to a multiservice network providing communication services.
2. Description of Related Art
Communication services today are generally based on either the public switched telephone network (PSTN), which provides circuit-switched voice services, real-time faxing and central office (CO)-based voice mail, or the Internet protocol (IP)-based Internet and Intranet, which provides services such as email.
The PSTN and the IP-based Internet and Intranets rely on different architectures and protocols. The PSTN refers to the collection of interconnected systems operated by the various telephone companies (telcos) and post telephone and telegraph administrations (PTTs) around the world. Although the PSTN was originally based on a human-operated analog circuit switching systems (plugboards), and progressed to include electromechanical switches, by now this has almost completely been made digital, except for the final connection to the subscriber (the “last mile”): The signal coming out of the phone set is analog. It is usually transmitted over a twisted pair cable as an analogue signal. At the telco office, this analogue signal is usually digitized, using 8000 samples per second and 8 bits per sample, yielding a 64 kb/s data stream (DS0). Several such data streams are usually combined into a fatter stream: in the US, 24 channels are combined into a T1 line, in Europe, 29 or 30 channels are combined into an E1 line. This can later be further combined into larger segments for transmission over high-bandwidth core trunks. At the receiving end, the channels are separated, the digital signals are converted back to analog and delivered to the received phone.
In IP-based wide-area networks, on the other hand, IP, transmission control protocol (TCP), and user datagram protocol (UDP) may be used to operate hardware and software data communication systems. These wide-area networks are usually constructed with serial lines, extending over distances greater than one kilometer. IP and TCP encompass both network layer and transport layer protocols to be used in such networks. UDP is a connectionless protocol which, like TCP, may be layered on top of IP. UDP neither guarantees delivery nor does it require a connection. As a result it is lightweight and efficient, but all error processing and retransmission may require care by an application program.
The PSTN and the IP-based wide-area networks are disparate systems relying on different designs and architectures. Melding the two systems together may require significant innovations and effort. There exists a commercial need for the design of a wide-area communication network offering services to the consumer, business and enterprise markets, which bridges communications across the PSTN, and IP-based Internets and Intranets.